In dentistry, probes having narrow, heated elements are used in root canal therapy for plugging a previously hollowed root system with heat-softened gutta-percha (natural rubber) or other substances. These heated elements are known as plugger elements or plugger tips and typically comprise plastically deformable stainless steel needle shaped members.
Methods and apparatus for heating these plugger elements are disclosed in U.S. Pat. Nos. 4,527,560 and 5,043,560, each issued to Masreliez, and the disclosures of which are hereby incorporated herein by reference. The heated plugger elements disclosed in the Masreliez patents are very thin and formed of stainless steel. Therefore, they are bendable to hold various shapes, but they are not significantly resilient or elastic.
The permanent deformability of conventional heated plugger elements requires the operator, such as an endodontist, to prebend the elements in an attempt to follow a curved root canal. However, it is very difficult to precisely conform the plugger element to the curvature of the canal in any particular case since the curvature must be approximated, for example, from an X-ray image. Moreover, even if bent in a relatively accurate manner, the permanent bend of the tip tends to make following the root canal difficult or impossible during the root canal procedure. This is especially true when the root canals have a compound curve or a curve with an increasing or decreasing radius. This results in inconsistent packing and shaping of the gutta-percha. Further, it is difficult to straighten the short, rigid plugger elements for reuse.
Another problem area not adequately addressed by prior plugger elements relates to the ability to twist the element during a root canal procedure. The ability to twist the plugger element during the procedure eases the release of the gutta-percha within the root canal. In this regard, in a typical procedure the root canal is filled with gutta-percha and a plugger element is inserted into the gutta-percha to force it into the lateral canals of the root. As the plugger element is inserted within a main canal of the root, the gutta-percha will be forced downward by the end of the plugger element and outward by the outer surface of the plugger element. This latter action forces gutta-percha material into the lateral canals. Twisting of the plugger element has then been used to break the frictional grip between the outer or side surface of the plugger element and the gutta-percha before the plugger element is pulled from the main canal. Rigid plugger elements having a present curvature cannot be adequately twisted by the dentist while they are within a curved main canal. Since these conventional plugger elements cannot be twisted to release the gutta-percha, most of the gutta-percha which is not forced into the lateral canals remains on the plugger element when it is removed from the root canal. The main canal must then be carefully refilled with gutta-percha.
To alleviate problems such as these in the prior art, it would be desirable to provide a temperature controlled dental probe having a reusable plugger element that conforms easily and precisely to root canals regardless of their curvature, and allows for easy release of filler material within the root canals.